The basic characteristics required of rubber vibration isolators are strength properties for supporting a heavy body such as an engine, and a vibration isolating performance which absorbs and suppresses vibrations by the supported body. Moreover, the rubber vibration isolator, when used in a high-temperature environment such as an engine compartment, in addition to having, of course, excellent strength properties, a low dynamic-to-static modulus ratio and an excellent vibration isolating performance, is also required to have an excellent heat aging resistance and excellent compression set. Furthermore, because automobiles are used even in high-latitude regions, automotive rubber vibration isolators are also required to have good low-temperature properties.
Research on compounding given amounts of a rubber component, a crosslinking system and other additives for a rubber vibration isolator in order to impart such collectively outstanding properties is actively underway, and numerous patent applications have already been filed. The art in most such disclosures provides outstanding heat aging resistance and dynamic-to-static modulus ratio, but falls short in terms of, for example, low-temperature properties.
The applicant earlier disclosed (JP-A 2012-229323) a rubber vibration isolator composition which, by virtue of the addition of a given proportion of N-phenyl-N-(trichloromethylthio)benzenesulfonamide to the compounding ingredients of a crosslinked system, has a better heat aging resistance and dynamic-to-static modulus ratio than in the pre-existing art. However, there remains further room for improvement in the low-temperature properties of the rubber vibration isolator.